


I can't believe my little brother is this cute!

by SesuRescue (Kigachan)



Series: Papyrus and Grillby doing totally normal couple things on the Surface [6]
Category: Undertale (Video Game)
Genre: Accidental Voyeurism, Anal Fingering, Anal Sex, Angst and Fluff and Smut, Blow Jobs, Cunnilingus, Dirty Talk, Ecto-Genitalia (Undertale), Ecto-Penis (Undertale), Ecto-Tongue (Undertale), Ecto-Vagina (Undertale), Explicit Language, Explicit Sexual Content, Face-Sitting, Feelings Realization, Fire Dick, Fontcest, Masturbation, Multi, Non-Consensual Voyeurism, Papby, Papysansby, Penis In Vagina Sex, Praise Kink, Size Difference, Surface Living, Threesome - M/M/M, Vaginal Fingering, sansby - Freeform
Language: English
Status: Completed
Published: 2017-07-29
Updated: 2017-07-29
Packaged: 2018-12-08 09:58:09
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,630
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11644146
Author URL: https://archiveofourown.org/users/Kigachan/pseuds/SesuRescue
Summary: Sans, while staying over at his brother's apartment, witnesses something he shouldn't have and figures out his feelings.





	I can't believe my little brother is this cute!

**Author's Note:**

> I've been wanting to write my OT3 for a while but didn't jump on it until a fellow writer helped persuade me by writing a super hot fic. Thank you @Megalotrash! The Papysansby empire will be glorious! 
> 
> This is literally the fastest I think I've ever finished a fic of this size, 14 days! How to Attract a Flame Elemental took me a solid month!

Sans rolled over on the couch, sighing as insomnia stole yet another good night of rest from him. He clutched the borrowed blanket closer to him as his eyelights took in the unfamiliar surroundings around him. 

Yesterday, he had woken up to find that his basement was flooded with water, a likely aftereffect of the rainy season. At first, Sans was willing to ignore it; it wasn’t the first time water had gotten in after all. However, when it started leaking into his kitchen he figured it was probably something to worry about. After calling his insurance and arranging for repairs to be done, he talked to Papyrus and made plans to stay at his and Grillby’s apartment until everything was done.

Ready to give up on trying to snooze, Sans sat up, determined to find the remote and watch television until he passed out from exhaustion. He got as far as pulling the blanket off of him before he was interrupted by keys jingling and loud obnoxious laughter coming from outside the front door. Not wanting to explain why he was still awake at  _ 2am? what the fuck _ , he ducked back under the covers and pretended to sleep. 

“SANSHH?? ARE YOU HERE??” Papyrus tried to whisper, coming out more like his normal volume, which made it almost deafening in the otherwise silent apartment. Grillby shushed him, letting out a rare bark of laughter. 

The door closed and footsteps crept towards him, the smell of alcohol wafting off of whoever was in front of him. He guessed they must’ve had a few drinks on their date night tonight. Had to have been a great night if they were just coming home now. Maybe Papyrus convinced Grillby to go dancing at a club with him? 

He concentrated on his ruse, keeping his eyes closed and relaxed as the person advanced closer, pulling the blanket off of his head. The sudden clack of a skull against his almost made him jump, but he kept his cool as the person— _definitely_ _papyrus—_ placed the blanket back and walked around to the other side of the couch.  

“He's Sleeping, It’s So Cute,” Papyrus cooed to Grillby. 

“Not as cute as you,” Grillby replied, the crackling of his flames enhancing the deep tones of his speech. 

Sans smiled to himself. He figured back when they started going out that Grillby would treat his brother right, but actually witnessing it was really sweet. Grillby really was such a great guy. So nice… caring… a great cook with a wicked sense of humor. Sans could talk to him about basically anything, and he did when he spent many a time in his bar past closing time. He  _ might _ have been pining after the gorgeous fire bartender for a while.  _ Too bad Papyrus got to him first.  _

He was so lost in his thoughts that he almost missed the sound of a slap reverberating throughout the apartment. Wait, was Grillby hurting his brother? Sans was ready to throw away his pretense of sleeping and throw the blanket off, magic blazing, but Papyrus’ laughter made him pause. 

“GRILLBY!” Papyrus gasped playfully. “How Naughty!”

Grillby reply came so softly that Sans couldn’t hear him, only the growling undertones of his words reached Sans’ ears. The slap must’ve been… oh. Sans flushed, realizing that Grillby definitely slapped Papyrus’ ass. Were they about to… 

A whine from Papyrus answered his question as the two of them started to make out above him, their tongues making wet, smacking sounds as they clashed together. 

“Nng, Grillby… Not Here, Sans Could Wake Up,” Papyrus groaned out between kisses. They stopped, Grillby grunting out something as their footsteps got further away.

Sans clutched at the rapid beating of his soul behind his ribs. Calm down Sans, he thought to himself. It's just your brother, making out with your old crush basically right next to you, no big deal. Definitely not something to get aroused over. He squinted down at his shorts, cursing the blue tint coming from his pelvis as his body betrayed him.

He listened out for any signs that the two of them were heading back, but he only heard soft sounds coming from what he assumed was the bedroom. Deciding that it was safe to retreat, he pulled the blanket off and flipped over onto his stomach, expecting to see the closed bedroom door. 

Instead, the door was half ajar, forgotten in the couple’s haste to get to the bed. Papyrus was seated in Grillby’s lap, head laying against the elemental’s chest and face scrunched up in arousal. Grillby’s cock was rutting against Papyrus’ summoned vagina lightly, making them both moan.

Sans flattened himself on the couch, burying his head in the cushions as he tried to get the image of his brother and Grillby out of his mind. His magic had fully manifested itself into a cock that was brushing up against him, killing any attempts of trying to get a hold of himself.

Just when he thought it couldn’t get any worse, he heard the sinful deep baritone of Grillby again. Despite himself, he focused on it. 

“... Look at you, so wet and ready for me,” Grillby purred. 

Sans exhaled, creeping his hand towards his shorts and imagining that the words were for him. He brushed his hand over the bulge, shuddering as his cock twitched from the attention. Was he really going to do this; masturbate listening to his crush fuck his brother?

A loud moan from Grillby helped him make his decision quickly as he freed his dick, groaning while wrapping his fingers around it. 

“Are you ready for my cock?” Grillby breathed, just loud enough for Sans to hear. His fingers teased his tip of his dick as he grazed his hand up.  _ fuck, yes please.  _

“Please, I Need It Inside Me!” Papyrus cried. 

Sans slowly worked his hand over his length as he listened to Papyrus beg from the other room. Somehow, his brother wasn’t turning him off but rather… it was arousing, to be honest. His hand paused as he mulled over that thought. He knew that his brother was attractive, and more than once he found himself wondering what it would be like, for Papyrus to act in the same flirting manner with him that he sometimes used with Grillby. How did he feel about his brother? Was he in l-

“AHHNN~!”

Sans jerked his head up, peeking over the couch cushion at the bedroom, just in time to witness Papyrus’ head thrown back in ecstasy as Grillby gripped his hips tight, bouncing Papyrus on his dick. His brother’s perfectly pristine bones shined in the light of Grillby’s flames, giving him an almost ethereal aura that captivated Sans. 

Putting a hand over his mouth to muffle himself, Sans redoubled his efforts, going far enough to grind his dick into the couch cushions for extra friction. He imagined himself as the one fucking Papyrus with his thick cock, making him scream. Bringing him to orgasm after orgasm. He also imagined himself with Grillby, hot flames licking his bones as the fire elemental fucked him silly. Maybe Grillby would even talk dirty to him, call him a filthy slut that needed to beg if he wanted to cum. 

Focusing back on the couple, Sans observed Grillby run his hand down Papyrus’ spine, lightly teasing him. Papyrus opened his mouth as if to complain, but a choked gasp came out instead as Grillby gripped his spine, pumping it to the rhythm of his thrusts.  Sans grinded harder into the couch, pushing himself closer to the edge. 

“Ah, Grillby! I’m Getting Close!” Papyrus warned. 

“Come for me, love.”

Papyrus stiffened on Grillby’s lap as he reached his peak, shouting. Seeing his brother's release threw Sans over the edge, giving a few more hard thrusts before he spilled himself all over the couch cushion. 

Sans all but collapsed into the couch, disregarding the sticky cum on his ribs as he took in labored breaths. Having genitals made of magic thankfully meant that any fluids would fade away rather quickly, so he wasn’t worried about a mess. 

Distantly, he heard Grillby grunt out his release, sending another wave of pleasure trickling down Sans’ spine. Man, that was amazing. Probably the best orgasm he'd ever had. The best orgasm he had ever had… And it was from watching his brother get screwed. 

_ Fuck.  _

Sans brought his hands to his face as dread filled him. He was disgusting, he couldn't think about his brother like that! His brother, with his tall lanky figure, his brash yet charming personality, his lovely pus—dammit, he liked his brother. 

What would Papyrus think of him, his dependable older brother, lusting after him like some sort of pervert? What would Grillby think? 

Sans’ sins weighed heavier and heavier on his back the more he pondered it. The apartment was quiet, save for soft snores coming from the bedroom as Papyrus and Grillby slept, blissfully unaware of the events that unfolded in their living room. Shifting onto his side, Sans’ saddled up for a long, intimate night with his inner demons. 

_______

The next day came and went as Sans went through the motions of acting normal. Papyrus woke him up early as usual for breakfast, dragging him and a hungover Grillby to the table for breakfast. Sans asked them how their date went, both flushing before explaining that their night out—which did end up being at one of Papyrus’ favorite clubs—went well. 

After a hearty breakfast, Sans all but ran out of the apartment, throwing an unusual amount of effort into his daily activities to drown out the confusing thoughts in his head. However, some things that became very clear to him throughout the day was that he wasn't quite over Grillby, and that he apparently was into his brother.  

At the end of the day, Sans found himself at Grillby’s bar, three drinks deep and maybe slightly inebriated. He tried joking with Grillby and the other patrons as usual, but judging by the way the elemental stared at him curiously all night, Grillby wasn't buying it. 

Sans tended to his latest drink, noticing that he was the last customer in the bar. Grillby stood across from him, cleaning a glass and staring straight at him. 

“...Is something wrong?”

Sans chuckled. “why would you think that, grillbz?” 

“... Sans, we’ve known each other for a long time, I think I can tell when my friend is hiding something.” Grillby set the glass on the table and leaned against the wall, crossing his arms. “... What’s going on?”

Sans downed the remainder of the drink in front of him. Even though his thoughts were fuzzy and muddled, his subconscious knew that he shouldn’t tell Grillby about last night. Nor should he tell him about his newfound sexual feelings for his brother. Or about his massive crush on him. Do not tell him about that crush thing.

“... Crush?”

_ Shit.  _ “uh, did i say that out loud?” Grillby nodded. “uhhhh…well, yeah. i might have a crush on you.” Sans scratched his skull, avoiding Grillby’s stare, though on the inside he was relieved. It was better to play his crush off as what was bothering him, instead of…everything else.

Grillby laughed, his voice popping and snapping like a fireplace as he pushed off the wall and propped his elbows up on the counter in front of Sans. “...I figured that out ages ago. Why bring it up now? Are you hiding something?”  _ Damn, am I really that easy to read? _

“uh...well...”

“...You can tell me anything, you know that.”

Sans sighed, peering down the counter as he gathered his nerve. Future sober him was going to hate him for what he was about to do, but he couldn’t lie to Grillby. “Well...last night I might’ve…watched you and paps have sex.”

Grillby flushed. “...Oh my gosh, I’m so sorry. We should’v—”

“don't apologize. i uh, liked it.” Sans said bluntly, surprising them both.

“...What?”

“i got turned on seeing you fuck my brother.” Wait no, Sans, stop. “i jerked off to the thought of having sex with both of you.” Oh my god, why are you telling him all of this. “i came all over myself to paps cumming on your cock.” Sans, you're digging a hole you can't come out of please cease and desist. “i like you a lot, and i’m into paps too.”

Sans took a deep breath, cursing his loose tongue. He scrutinized Grillby, whose expression had been utterly blank since the start of his word vomit.  This was a bad idea, he knew it. He could tell Grillby anything but... this was too much. At least it couldn’t get any worse, right?

A gentle thud echoed from the front of the restaurant, causing them both to jump. Sans whipped his head around to spot Papyrus, whose eyes were wide and fingers were loosely gripping the strap of his work bag, which had been the source of the noise.

“S-sans? W-what did you just say?” Papyrus breathed out shakily.

“i… uh.” Sans started to speak, before the full weight of the situation hit him. His brother must think he's some sort of freak, a weirdo.

Of all the things he could deal with, the number one thing he couldn't handle was Papyrus being disgusted with him, so he took the only option he had. With a pop, he teleported away. 

_____

Sans woke up slowly, staring at yet another unfamiliar ceiling above him. Where was he? He let his thoughts float back to him, slowly piecing together the events from the night prior. He was tipsy, he declared his love for Papyrus basically right in front of him, and then he teleported to the nearest inn to stay the night. Probably should apologize to the front desk for just  _ popping _ in like that later. Heh. 

He sat up, rubbing his skull as he picked up his phone to survey the damage. Ten missed calls, twenty unread messages, and who knows how many voicemails. Youch. Ignoring the notifications, Sans pocketed his phone and rolled out of bed. He knew he had to apologize to Paps and Grillby at some point, but he wasn't ready to face them yet. Luckily, he knew their schedule like the back of his hand, and right now they were both working. It was the perfect time to sneak over, grab his things, bring them back here to his room, and wait for this whole thing to blow over, or at least until he could gather the courage to apologize. Sans channeled his magic and teleported to Papyrus’ apartment. 

He landed on the couch, letting out a small ‘omph’ when he didn’t connect with the soft cushions, but instead onto something hard.

“SANS?!” Sans stared in surprise at the wide eyelights of Papyrus, the number one person he didn't want to interact with today.  _ Shit.  _ Sans prepped his magic to teleport back to his inn room, but suddenly his body was rooted to the spot. He glanced down to find that his body was surrounded by a blue tinge.

“uhhh, did you use blue magic on me, bro?” Sans chuckled nervously.

Papyrus picked him up, turning him around so that Sans was facing him. “Yes Sans, I did! You’re not running away again until we talk about this!”

Grillby popped his head out of the bedroom. “... Did he come back?”

“Yes, I’ve got him!”

Sans felt his anxiety skyrocket as Grillby shambled over to the couch beside them, yawning. He hadn’t had much of a good night's sleep, if the dark pools of magma clustering underneath his eyes were any indication.

“hey grillbz, how’s it going? you don’t look so  _ hot _ , heh,” Sans joked, trying to lighten up the tense atmosphere. 

Grillby’s face was blank. “...We were up all night, worried about you. You didn’t answer your phone or message us; we had no idea what happened to you.”

“yeah, i stayed at the inn for the night.”

“Sans, why didn’t you just come back to the apartment?”

Sans turned his attention back to Papyrus, squirming under his gaze. “i didn’t want it to be weird, you know since your older brother has illicit feelings for you and all. paps, I promise i’ll never bring it up again, and if you don’t want to see me again…” Sans gazed directly into Papyrus’ eyes. “...well then, I’ll respect that wish.”

Papyrus enveloped Sans into a tight hug. “Sans, you ALWAYS come to the worst conclusions without considering the other side of the equation,” Papyrus murmured against Sans’ skull.  “Did you ever stop to think that maybe I felt the same about you?” Papyrus pulled back and held a hand up to Sans, silencing any interruptions. “I’ve had not-so-brotherly feelings for you for a while, Sans, but as expected of the Great Papyrus, I am a master at hiding it. I figured I shouldn’t burden you with it, so I never told you.”

“After Grillby and I became serious datemates, I disclosed my feelings about you, because I didn’t want to hide anything from him. He accepted me and my feelings. Surprisingly, he feels the same way about you, too.” Papyrus winked. 

Sans, finding that he could control his body again, whipped his head around to a blushing Grillby, who nodded. 

“so, it’s okay for me to love you?” Sans asked quietly. 

“Grillby and I had a long discussion about this last night and, should you want to be datemates, you’ll have to date both of us. I like you two quite a bit and would rather not have to choose between you.”   
  


Sans started to chuckle, the absurdity of all of it crashing into him all at once. He could hardly believe it, but Papyrus didn’t hate his guts, he loved him! Grillby loved him too! His laughter dissolved into small sobs as he lowered his head towards Papyrus’ ribcage, clutching the other’s shirt for leverage as relief set in. Papyrus pulled Sans back into his chest, rubbing small circles onto his back. 

“Shh, it’s okay. You don't have to fret about sharing, I promise there's more than enough of me to go around.” Papyrus reassured him. Sans let out a quick laugh between sobs. 

“that's not it, i’m just really happy that you don't hate me, or think i'm gross.” Sans looked up at Papyrus. “is it alright if i kiss you?”

“I'd be offended if you didn't, Sans.” 

Sans nodded, stretching up hesitantly, before clacking his teeth against Papyrus’. Papyrus hummed, his hold on Sans tightening as he deepened the kiss. 

They sat like that for a bit until Sans broke the kiss. His cheeks were blazing and bright blue as he gazed into Papyrus’ eyes. “wow, that was…”

“Amazing,” Papyrus finished, his cheeks just as bright. 

“what do we do now?” Sans asked. 

“Well, I know you won't believe me if I tell you but, Grillby and I are really fond of you. If you’ll allow it, we would like to show you just how much we love you… physically. In bed.”

Sans’ thought process grounded to a halt as he took in this information. The two of them, sharing a bed with him…  _ Jesus.  _ Sans peeked over for confirmation from Grillby, who was just about comatose before, startled at the intense, lustful gaze Grillby had fixed upon him. They both...wanted him? He considered his options, knowing that he could tell them no, but really, who was he kidding? These two gorgeous men, of course there was only one way to answer.

“i’d like that.”

Papyrus smiled at him, standing and carrying Sans in his arms as he walked towards the bedroom, Grillby hot on his heels. 

Grillby entered first and sat on the bed, scooting back until his back was flush against the headboard. He opened his legs for Papyrus to deposit Sans into, his back in front of Grillby’s chest. It was so cozy, like being surrounded by a warm, fluffy blanket, so Sans couldn't help reclining back into him. 

“... warm?” Grillby rumbled. 

“yeah, feels nice grillbz. you really know how to  _ heat _ me up.” 

Grillby laughed, massaging Sans’ sides as Papyrus sat down in front of them, frowning.

“Sans, please refrain from making your terrible puns in the bedroom, and you”—Papyrus paused to bend forward so that his teeth were inches away from Grillby’s mouth—“don't encourage him or we'll be listening to them all day.” Papyrus pressed a chaste kiss to Grillby, before bending down to claim Sans’ mouth in a kiss. 

Sans melted into it, tongue forming to wrap around Papyrus’ own. He pressed harder into the kiss, tilting his head to get a better angle as his hands lingered on Papyrus’ hips. 

Just as he was relaxing into it, a gentle caress against his spine made him break the kiss, arching his back and mewling. Grillby laughed behind him, using the opportunity to lift Sans’ shirt over his head. Papyrus let his hands smooth over Sans’ thigh bones, catching his shorts and pulling them down to expose his pelvis. 

“Wow, my spine is super sensitive too! I wonder if the rest of your sensitive spots are like mine…” Papyrus moved his hands higher, focusing his attentions on Sans’ upper half.

Noticing how exposed he now was, Sans blushed, moving his hands to try and cover his bare pelvis. However, before he could reach it, his hands were grabbed and held together in front of him in one warm flame hand. 

“...Don’t be embarrassed Sans, you’re ravishing.” Grillby placed his hand on Sans’ inner thigh, spreading his fingers apart to grip and caress it. “...Your bones are nice and smooth,” Grillby paused to lick the back of his neck, “...Tasty too.”

Sans shuddered, resting his head back against Grillby as the flame tongue lapped at his neck aggressively. It was so different, much warmer compared to the cold ecto tongue that he and Papyrus could conjure. He really liked it.

Papyrus, finding the perfect opportunity to overwhelm his brother, slipped his phalanges into Sans’ ribcage to rub at the inside of his ribs. He captured the other's mouth in a kiss to swallow the loud whines that Sans let out, moving their tongues together in a fight for dominance. Their bones clacked against each other as Papyrus scooted closer to Sans, basically in his lap as he continued the assault on Sans’ mouth and ribs. 

“... Wow, the two of you are so sexy together,” Grillby muttered, shifting slightly so that his arousal was brushing up against Sans’ tailbone. Grillby’s hand, which had been slowly making its way to his pelvic cavity, massaged the magic forming there, coaxing it to take form. 

Sans’ thoughts were a mess of static as he tried to process all the different sensations. Papyrus was expertly drumming his fingers along the insides of his ribs, making him slightly buck up into Grillby’s hand on his magic. Grillby was also grinding his warm dick right against one of his most sensitive parts! He gave up trying to take charge the kiss a while ago, content to let Papyrus lead the way in exploring his mouth and tangling their tongues together. He tasted like…cinnamon? It was so good, he could get used to this. 

One particular thrust from Grillby had him yelping into the kiss as his magic finally settled into a plump vagina. 

Papyrus broke the kiss, placing one last peck on Sans’ teeth before leaning back. His cheeks were bright orange and he his ribcage was expanding and contracted rapidly, despite not needing to breathe. Sans let his eyelights roam further down, pausing and gawking at the huge bulge tenting Papyrus’ pants. Holy fuck, was that going into him?! 

“is that going to fit?” Sans asked, uneasy as he watched Papyrus take off his shirt and fold it. 

“...Don't worry, I know it's pretty daunting but Papyrus is very good at preperation.” Grillby turned Sans around in his lap to face him and Sans saw the reaction all of this was having on him. His face was almost entirely blue, and his flames had grown at least twice their normal size to flicker violently around him. Sans didn't even notice the room heating up, so he guessed that Grillby might've been loosely manipulating the temperature of his flames. 

“ _ tibia  _ honest, i feel like that is gonna split me in two.” Sans smiled at Papyrus’ exasperated voice behind him, though he was quickly surprised as he was lifted backwards from Grillby’s lap. 

“Must I suffer through your puns even during sex??” Papyrus held him up as he laid down on the bed, positioning himself under Sans. “Lucky for you, I am a courteous lover. Despite my anger, I will thoroughly prepare you to quell your concerns.”

Papyrus buried his face into Sans’ folds, crying out in appreciation as his tongue slipped further inside to lap at the inner walls. 

Sans groaned, placing his hands on either side of Papyrus. Shit, this was amazing, how was Paps so good at this? 

“...He’s really eager to please,” Grillby responded to the unasked question as he stood, shedding his clothes.  “...He’s a very good boy, aren’t you Papyrus?”

Papyrus hummed underneath Sans, lifting one of his hands to give a thumbs up gesture. 

Grillby leaned in close to kiss Sans on the teeth, before walking out of his vision. “...You know what good boys deserve, right?”

Sans jolted as Papyrus’ hands suddenly tightened around his hips, pulling out of Sans slightly to let out a moan. “Ohhh my god, Grillby!” Before Sans could ask what was going on, two fingers plunged into his entrance. 

“Fuck, paps!” Sans hissed, fisting his hands into the sheets and gyrating his hips against the fingers inside him. Papyrus’ thumb joined the assault as it ground down against Sans’ clit, making him see stars. Just when he thought he could handle all the pleasure, Papyrus started to rock his fingers in and out of his entrance, stretching them apart. 

“bro, i’m getting close,” Sans warned as the familiar coil feeling started creeping up on him. Papyrus however, didn’t stop; if anything, he went harder as he flicked his tongue against Sans’ clit. Gasping, Sans could only bend over into the bed as his orgasm washed over him, drenching Papyrus and the sheets under him with cum.

“I didn’t know you were a squirter,” Papyrus commented as he placed Sans on the bed beside him, licking at his teeth.

“neither did i.”

Sans wasn’t sure what was hotter; his cum-drenched brother or the new beautiful picture he had of Grillby kneeling on the floor, pulling his fingers out from inside of Papyrus’ summoned asshole. “is that what you’ve been doing the entire time?” Sans asked playfully. “i was so  _ bonely  _ up here without you.”

Suddenly, Sans was pushed down face-first into the bed, his ass up in the air as Papyrus loomed over him. “Brother, I have warned you time and time again about your puns, and that’s strike three. Now, should you consent to it, I’m going to give you the punishment you deserve.”

“how can i say no to that? but um...oh geez, how do i ask this...” Sans trailed off, thinking. “can i suck grillbz’s cock during it?”

Grillby sputtered, standing up. “...me?”

“gotta make sure you’re well lubricated if you’re gonna fuck Papyrus, don’t you think?”

Papyrus shrugged. “If Grillby is up for it, I have no issue with it. Grillby?” 

“...Honestly, I would love nothing more.”

“then it’s settled, fuck me up bro.”

The three arranged themselves so that Papyrus was hovering behind Sans, dick rutting against his entrance, and Grillby was kneeling in front of Sans, his dick pulsing right in front of Sans. Sans knew he needed that cock in his mouth right now. He stuck his tongue out and licked a long stripe up the side.

“mmm, hey grillbz.”

“...Yes?”

“i’m  _ burning  _ up for you.”

“...” Grillby stroked Sans’ skull with his hands, before guiding his mouth onto his cock without a word. At the same time, Papyrus slowly pushed his cock into Sans’ pussy, hissing in pleasure as he went in deep.

Geez, Papyrus’ cock was just… So big! He whimpered around Grillby’s cock, scrambling to hold onto anything that would make the adjustment easier.  

“...Shh, you’re doing so well, it’s almost all in you. A little bit longer and it’ll start to feel amazing, I promise,” Grillby reassured him.  Sans practically glowed from the praise, his pussy spazzing around Papyrus’ dick and making him groan in turn.

They sat there for a short while, Papyrus and Grillby soothing Sans however they could while he adjusted to the huge length he was taking. Eventually, Sans decided he was comfortable, and experimented with wrapping his tongue around Grillby’s dick. 

Surprisingly, for a man made purely of fire, he was quite solid, even down to his dick. As Sans sucked the cock like his life depended on it, he noticed that the flames were almost...following his path. How neat. He dragged his tongue in patterns on Grillby’s dick, mesmerized by the complex patterns the fire was imitating. Judging by the panting coming from Grillby, he doesn’t seem to mind Sans’ exploration.

Papyrus, recognizing that Sans was finally comfortable, started to thrust in and out of Sans. “Ahhhhh, you feel so great around me!” Papyrus exclaimed, his tongue lolling out and dripping onto Sans’ back. Sans blushed, the praise turning him on to no end. He tried to hide how it was affecting him, but as usual Grillby read him like an open book.

“...You have a praise kink.”

“mm, i guesh,” Sans replied, mouth full, adding his hands to the mix. Grillby gently pried Sans off his dick and scooted back on the bed until his head was against the headboard. 

“...Sorry,” Grillby breathed out, “If we kept going like that you were going to make me cum. While your mouth is exquisite, I think Papyrus has something else in mind.”

“I do!” Papyrus stilled his hips, lifting Sans up and off his cock. He placed himself in Grillby’s lap, effortlessly taking Grillby’s dick up his ass in one shot. Sans whistled as he crawled over to the two of them, eyeing where they were connected.    
  


“wow, you’re a well-seasoned veteran, bro.”

“Of course, I am. I worked hard to be able to do this. Are you ready?”

Instead of verbally answering, Sans climbed in between Papyrus and Grillby, lowering himself back down onto Papyrus’ dick. Grillby set the pace, slowly thrusting into Papyrus, who ended up moving deeper into Sans’ entrance. 

“fuckkkk,” Sans wheezed out, his pussy spread to its limit. He rested back against Grillby’s chest as the other’s movements transferred to him. It didn’t take long for them all to find a rhythm, Grillby’s arms around Papyrus and Sans as he grinded into Papyrus. Sans was caressed and nuzzled by the two of them as they took turns kissing him and whispered praises into his ear, flustering him to no end. 

Sans thought that being around the two of them, who dwarfed him in size, would cause him to feel self-conscious, but to his delight it didn’t. He felt...safe and protected in their arms. If Sans had any lingering doubts about all of this before, he was sure that now they were all gone. He loved these two, and dammit he was going to date them and they were all going to be happy together. 

Sans knew that he wasn’t going to last any longer, and from the expressions of the other’s faces they probably weren’t either. The rhythm started to stutter as Grillby suddenly gasped, breathing heavily. “...I’m going to cum!”

“Please Grillby, do it!” Papyrus whined out, skull against Sans’ as he gritted his teeth together. Grillby slammed his hips up once more before cumming, his release explosively reaching past Papyrus’ ecto-genitalia to splash up and against both skeleton’s ribs, coating them in a hot lava-like substance. Papyrus quickly followed, going as deep as he could into Sans, his cum joining Grillby’s on Sans’ ribs. Finally, Sans came, squirting on Papyrus dick. 

They held each other tightly, concentrating on breathing and remembering how to move again. Sans’ and Papyrus’ ecto-genitalia fizzled out of existence, leaving Grillby’s cum to dry on their ribs. Sans started to pick at the solid rock on his ribs, fascinated, but Papyrus gently coaxed his hands away from his ribs.

“You don’t want to peel it off like that, Sans, it will hurt. Soap and water is really effective for it. We can take a shower later and peel it off together, okay?”

Sans nodded, climbing off of Papyrus and collapsing on the bed. Papyrus and Grillby laid on either side of him.

“...How was it for you, Sans? I know everything happened very fast.”

Sans rested his head against Grillby. “it was seriously the best experience of my life, thank you so much.”

“...Well, like we said earlier, Papyrus and I were seriously about asking you to date both of us. We love you a lot, and we want to deepen our relationship with you.”

“i would love nothing more to date you two, if you’ll have me.”

Papyrus tittered beside him. “Sans, have more confidence in yourself, like I do!” He frowned. “We skipped a few steps in the dating manual, but for once I’ll allow it. We are officially all datemates now!”

Sans yawned, suddenly exhausted from all the activity. “i’m really excited about everything, but let's discuss it more after a quick nap, i’m beat.” He snuggled between his two new lovers, sighing happily.

**Author's Note:**

> A moment of silence for the fathom joke that unfortunately couldn't make it into this fic.
> 
> Thank you so much for reading this self-indulgent fic! Feel free to bother me at my NSFW Tumblr:[Sesurescue](http://Sesurescue.tumblr.com)


End file.
